[exim] Infinite Loop With 'no such address'

Hello All:

I do not know if this is a exim problem or a user-agent problem, but
it seems that when someone sends a message to an non-existing address,
in the logs it shows rejected RCPT <blahlabh@???>: no such
address here -- but this message just keeps looping again and again
(going on for three days now)

It this something in exim, or that the client is just resending the
same email with the wrong address? Any hints on solving this problem
of looping?

Regards,
Burhan